<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>透明的单例类的编写优化版</title>
</head>
<body>
<button id="loginBtn">
    登陆
</button>
<script>
    var loginLayer = (function () {
        var div = document.createElement('div');
        div.innerHTML = '我是登陆浮窗';
        div.style.display = 'none';
        document.body.appendChild(div);
        return div;
    })()
    document.getElementById('loginBtn').onclick = function () {
        loginLayer.style.display = 'block';
    }
</script>
</body>
</html>